This invention relates to an adsorber for hemoperfusion to remove soluble poisonous substances contained in blood by means of adsorption.
Patients of renal failure or liver failure suffer reduced ability to excrete soluble poisonous substances such as creatinine, uric acid, urea and protein-bound substances from their blood, resulting in an accumulation of such poisonous substances in their blood which endangers their lives. To prevent this, dialysis or use of adsorbents has heretofore been employed to remove these poisonous substances and thereby decontaminate the blood. However, since dialysis is a means of decontamination using a semipermeable membrane, it is rather difficult to effectively remove substances of middle or large molecules and protein-bound substances represented by bilirubin.
Another means of decontamination is to bring an adsorbent into direct contact with blood to adsorb poisonous substances, allowing various poisonous substances to be removed from blood if the type of adsorbent is selected properly. With this type of decontamination, the adsorption of poisonous substances contained in blood is carried out by liquid phase adsorption. In general, it is desir-able to use an adsorbent in the form of powder or fine particles having a large surface area, because substances have a smaller diffusion velocity in the liquid phase than in the gaseous phase, and the adsorption velocity is consequently dependent on the surface area of the adsorbent. However, adsorbents in the form of fine particles having a large surface area cannot be safely used, because they would flow into the human body. Thus, in order to effectively decontaminate blood by the use of an adsorbent in the form of powder or fine particles, it becomes essential to fix the adsorbent by some effective means. Several methods have been proposed for mixing a high-molecular weight material and an adsorbent and fixing them into a spherical or membraneous form, as described in Artificial Organs, Vol. 4, 302 (1980) and Vol. 6, 151 (1982) and Japanese Patent Publication No. 32636/1978. These methods are inadequate because the ratio of the high-molecular weight material to the absorbent has to be great enough to adequately maintain such a fixed state, with the result being that the high-molecular weight material layer on the surface of the adsorbent will become thicker and the adsorptivity will be greatly reduced.
A method of using a particulate adsorbent coated with a thin layer of a high-molecular weight material has been proposed in Japanese Patent Publication Nos. 3944/1980 and 27090/1981. This method is still inadequate because poisonous substances are transformed so slowly into the adsorbent that a satisfactory adsorption velocity can hardly be expected.